docs: def update_backward_window(turn_from, tick_from, turn_to, tick_to, updfun, branchd):
      """Iterate backward over a window of time in ``branchd`` and call ``updfun`` on the values"""
      if turn_from in branchd:
          for future_state in reversed(branchd[turn_from][:tick_from]):
              updfun(*future_state)
      for midturn in range(turn_from-1, turn_to, -1):
          if midturn in branchd:
              for future_state in reversed(branchd[midturn][:]):
                  updfun(*future_state)
      if turn_to in branchd:
          for future_state in reversed(branchd[turn_to][tick_to+1:]):
              updfun(*future_state)